水酶法提取大豆油脂的扩大试验研究

水酶法提取大豆油的研究已经取得了很大的进步,因此在实验室规模基础上,进行了水酶法提取大豆油的扩大试验。在10 L反应釜中,每次试验需要1.2 kg的挤压膨化大豆片。通过单因素和响应面试验对加酶量、pH、酶解温度、酶解时间和料液比进行参数优化,得出最优结果:加酶量1.92%,p H9.15,酶解时间3.09 h,酶解温度56.15℃,料液比1∶5.04,油脂提取率(69.02±0.55)%。并且,通过透射电镜和光学显微镜观察、研究,揭示出水酶法提取大豆油的释放机理,以便于提高水酶法的油脂提取率和油的品质。最后,通过比较水酶法和溶剂浸提法,结果表明:水酶法提出的大豆油品质更好,过氧化值更低。     

琥珀酰化对水酶法提取大豆蛋白的影响

大豆蛋白是大豆水酶法的主要副产物,提高大豆蛋白提取率对于更好地实现大豆水酶法副产物的综合利用意义重大。通过将琥珀酰化与水酶法相结合,研究了加酶量、液料比、琥珀酸酐添加量、酶解时间和改性时间对总蛋白提取率的影响,并利用响应面分析法优化出最佳改性工艺参数:加酶量为2.24%,液料比为5.25∶1,琥珀酸酐添加量为5.13%,酶解时间为3.21 h,改性时间为1.64 h。在此条件下的总蛋白提取率为93.01%,多肽提取率为66.02%,与改性前相比分别提高了4.37%和23.46%。     

高压CO2对水酶法乳状液破乳影响的研究

研究高压CO2破乳过程中的各种因素对破乳效果的影响,并采用透射电镜来观察乳状液破乳前后油脂和蛋白的变化情况。在单因素基础上通过响应面优化得到最佳破乳条件:高压CO2压力为13.96MPa,温度155.64℃,处理时间21.46 s,浓度0.53 g/cm3,破乳率最优值(94.88±0.30)%。并且通过透射电镜观察发现,破乳前乳状液中大部分油脂被蛋白牢牢包裹,然而破乳后乳状液中包裹油脂的蛋白被破坏,油脂释放并结合在一起。     

微波辅助生物解离法提取大豆油工艺及作用机理研究

对微波辅助生物解离法提取大豆油工艺及作用机理进行了研究,采用微波技术对大豆进行预处理,然后采用Protex 6L碱性蛋白酶对其进行酶解提油。在单因素试验的基础上,通过响应面试验设计优化了工艺条件。通过透射电镜和拉曼光谱分别对微波处理后大豆和蛋白质进行分析。结果表明,各因素对总油脂提取率的影响大小依次为微波时间、Protex 6L添加量、液料比、微波功率。微波辅助生物解离法提取大豆油的最佳工艺条件为微波功率700 W、微波时间7. 6 min、Protex 6L添加量0. 90%、液料比为5. 15∶1,在此条件下总油脂提取率为92. 13%。利用微波辅助生物解离法提取的大豆油品质较好,过氧化值、p-茴香胺值及磷脂含量较低。通过透射电镜图可以看出,大豆经过微波处理后,大豆细胞壁组织发生更为明显的破裂是总油脂提取率增大的重要原因。拉曼光谱分析表明,经过微波处理后蛋白质发生变性,也是增加总油脂提取率的原因之一。     

Isolation of peanut protein aggregates using aqueous extraction processing combined with membrane separation

A two-stage microfiltration and ultrafiltration (MF/UF) for peanut protein recovery and water recycling from aqueous extraction processing (AEP) were investigated. Peanut protein aggregates and alkaline water were obtained using flat and wound MF/UF and alkaline water recycled in AEP. With this approach, most of the wastewater could be recycled to produce reusable water to solve wastewater problems in aqueous oil extraction processing from oilseeds. The result showed that a little oil and protein were lost (1.21% and 4.35%, respectively) during the recycling of permeate in AEP, which was still acceptable. Peanut protein aggregations (PPAs) were characterised by analysis with Fourier-transform infrared spectroscopy (FTIR), sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), high-performance gel filtration chromatography (HPGFC) and binding force analysis. Solubility analysis suggested that PPA had molecular structures with more hydrophobic groups on the surface than in the peanut protein isolate (PPI). In vitro, PPA was digested by both pepsin and trypsin more than PPI. FTIR profiles demonstrated there were more β-sheet and less α-helix in PPA, which means much more aggregation. In addition, binding force analysis showed hydrophobic interaction was the major force that restricted dissolution of PPA and disulfide bonds were of second importance, which provided a possible physical treatment opportunity for improving the solubility of PPA.     

粗酶水相提取大豆油过程中蛋白酶解与油脂释放状态

为了考察粗酶水相提取大豆油过程中蛋白酶解和油脂释放状态,监测酶解过程中总油、总蛋白提取率以及蛋白相对分子质量变化,同时采用扫描电镜、考马斯亮兰与苏丹红Ⅲ染色显微观察技术研究酶解过程中油脂和蛋白在豆粉、水解液、乳状液中的分布状态。结果表明:随酶解时间延长,蛋白酶解程度加深,油脂释放量提升,水解蛋白中相对分子质量大于33 000 Da的多肽含量逐渐降低,而相对分子质量小于5 500 Da的短肽含量增加。酶解6 h时,总蛋白和总油提取率均达到最高,分别为90. 1%和94. 2%,此时蛋白水解液中短肽(5 500 Da)含量最高,占49. 63%,相对分子质量大于33 000 Da的多肽仅占21. 15%。扫描电镜图显示由于酶解作用豆粉内的蛋白和油脂逐渐被分解和释放,原本充盈的细胞转变为空的残渣。光镜图显示,伴随豆粉酶解,水解液中蛋白含量逐渐增加,释放的油脂在水解液和乳状液中均有分布,随酶解时间延长油滴数量增加、粒径增大。     

Modeling yerba mate aqueous extraction kinetics: Influence of temperature

A new kinetics model, a combined second-order-diffusional kinetics model, was developed and compared with a pseudo first-order model for the aqueous extraction of total water soluble solids (WSS) from yerba mate leaves. The model that coupled two mechanisms fits the experimental data more satisfactorily (E% = 1.2 to 2.2) than the pseudo first-order model (E% = 3.9 to 4.4). The second-order-diffusional model could explain the first seconds of the WSS extraction and how the different mechanisms contributed to the concentration of the extract. Temperature influenced the kinetics parameters, but the equilibrium concentrations and the extraction yield were not significantly influenced in a temperature range between 40 and 70 °C.     

Characterisation of peanut protein concentrates from industrial aqueous extraction processing prepared by spray and freeze drying methods

Peanut protein concentrates (PPCs) were prepared by aqueous extraction processing (AEP), organic solvent extraction processing (SEP) and prepress-organic solvent extraction processing (P-SEP) and converted into powder by freeze and spray drying. The drying method showed an influence on the surface morphology and second structure of PPCs. Peanut protein concentrates of AEP were found to have lower protein contents, solubility and higher surface hydrophobicity, resulted in similar emulsion ability index (EAI) values and lower emulsion stability index (ESI) and water-holding capacity (WHC) values compared to PPCs of SEP and P-SEP. Foaming capacity was barely affected by oil extraction processing and drying methods, foaming stability was significantly influenced by oil extraction processing. Freeze-dried PPCs had higher solubility, WHC and fat absorption capacity than spray-dried PPCs, which was not the case for EAI and ESI. Hence, PPCs of AEP showed adequate functional properties, making AEP more appropriate for phytoprotein beverages.     

Impact of high-pressure processing on microbial shelf-life and protein stability of refrigerated soymilk

The effects of pressure (400, 500 and 600 MPa), dwell time (1 and 5 min) and temperature (25 and 75 °C) on microbial quality and protein stability of soymilk during 28 days of storage (4 °C) were evaluated under aerobic and anaerobic conditions. After processing and during storage, there were significant differences in total bacterial count (TBC), numbers of psychrotrophs (PSY) and Enterobacteriaceae (ENT), and protein stability between untreated (control) and pressurized samples (P < 0.05). Pressure applied at an initial temperature of 75 °C resulted in a greater suppression in growth of PSY compared to TBC. No ENT was detected in pressurized samples throughout the storage period tested. Dwell time had no significant effect on log reduction of TBC at 25 or 75 °C (P > 0.05). Pressure at 400 MPa (5 min), 500 and 600 MPa (1 and 5 min) produced 100% sub-lethal injury in surviving bacterial populations irrespective of temperature. After 28 days of refrigerated storage, both aerobic and anaerobic pressurized samples had better or similar stability as the control on day one of storage. Soymilk control samples were spoiled after 7 days whereas pressurization increased soymilk shelf-life by at least 2 weeks. Pressure (600 MPa) at 75 °C for 1 min not only significantly reduced initial microbial populations and increased the microbial shelf-life but also extended the protein stability of soymilk (P < 0.05).     

挤压加工和环膜制粒工艺对饲料氨基酸稳定性的影响

本文采用挤压加工和环模制粒工艺生产添加有晶体氨基酸(CAA)或微胶囊氨基酸(MAA)的水产颗粒饲料,研究2种加工过程对饲料CAA和MAA的损失,及其在水中的稳定性效果,旨在阐明挤压加工和环膜制粒工艺对饲料CAA和MAA稳定性的影响。结果表明,饲料加工对CAA和MAA的损失没有显著性差异(P>0.05),相比MAA,在饲料加工过程中晶体赖氨酸(C-Lys)和蛋氨酸(C-Met)分别多损失0.37%-8.02%和1.16%-4.29%;加工饲料的CAA在水中的损失较大,饲料水中浸滤60 min时,不同挤压温度饲料C-Lys比M-Lys多溶失23.99%-40.68%,C-Met比M-Met多溶失9.0%-13.5%;饲料水中浸滤120 min时,不同挤压温度饲料C-Lys比M-Lys多溶失24.42%-43.22%,C-Met比M-Met多溶失10.45%-17.47%。挤压温度的升高增加了氨基酸的热损失,但改善了饲料氨基酸在水中的溶失;MAA改善了CAA在饲料加工过程损失和水中的溶失。     

真空挤压膨化水酶法提取大豆油的工艺研究

对水酶法提取大豆油真空挤压膨化工艺进行了研究,在单因素试验基础上,采用响应面优化方法确定真空挤压膨化工艺的最优条件为：套筒温度为86.85℃、真空度为-0.067MPa、模孔孔径为22mm、螺杆转速为91r/min、物料含水率为16%,总油提取率可达到93.87%,比传统的湿热预处理后酶解的总油提取率提高了约21个百分点。     

Use of mild-heat treatment following high-pressure processing to prevent recovery of pressure-injured Listeria monocytogenes in milk

This study examined the inactivation of Listeria monocytogenes in milk by high-pressure processing (HPP) and bacterial recovery during storage after HPP. We developed a technique to inhibit the bacterial recovery during storage after HPP (550 MPa for 5 min) using a mild-heat treatment (30-50 degrees C). Various mild-heat treatments were conducted following HPP to investigate the condition on which the bacterial recovery was prevented. Immediately after HPP of 550 MPa at 25 degrees C for 5 min, no L. monocytogenes cells were detected in milk regardless of the inoculum levels (3, 5, and 7 log(10)CFU/ml). However, the number of L. monocytogenes cells increased by >8 log(10)CFU/ml regardless of the inoculum levels after 28 days of storage at 4 degrees C. Significant recovery was observed during storage at 25 degrees C; the bacterial number increased by >8 log(10)CFU/ml after 3 days of storage in the case of an initial inoculum level of 7 and 5 log(10)CFU/ml. Even in the case of an initial inoculum level of 3 log(10)CFU/ml, the bacterial number reached the level of 8 log(10)CFU/ml after 7 days of storage. No bacterial recovery was observed with storage at 37 degrees C for 28 days. Milk samples were treated by various mild-heat treatments (30-50 degrees C for 5-240 min) following HPP of 550 MPa at 25 degrees C for 5 min, and then stored at 25 degrees C for 70 days. The mild-heat treatment (e.g., 37 degrees C for 240 min or 50 degrees C for 10 min) inhibited the recovery of L. monocytogenes in milk after HPP. No recovery of L. monocytogenes in milk was observed during 70-day storage at 25 degrees C in samples that received mild-heat treatments such as mentioned above following HPP (550 MPa for 5 min). Moreover, the mild-heat treatment conditions (temperature and holding time) required to inhibit the recovery of L. monocytogenes in milk was modelled using a logistic regression procedure. The predicted interface of recovery/no recovery can be used to calculate the mild-heat treatment condition to control bacterial recovery during storage at 25 degrees C after HPP (550 MPa for 5 min). The results in this study would contribute to enhance the safety of high-pressure-processed milk.     

Effect of high-pressure processing on volatile composition and odour of cherry tomato purée

The impact of high-pressure processing on the odour of cherry tomato purée was evaluated by sensory evaluation and SPME–GC/MS analysis. Two temperatures (20 and 60 °C) and two pressures (atmospheric and 800 MPa) were used in processing. Higher pressure at ambient temperature decreased the levels of certain volatile aldehydes, ketones and alcohols present in tomato, whereas, the levels of hexanal, heptanal and octanal increased. The higher temperature combined with either ambient or high-pressure, decreased the levels of many volatile compounds and caused a reduction in the intensity of fresh tomato odour. Processing at 800 MPa and 60 °C resulted in a marked increase in the intensity of cooked tomato and tea-like odour. On the basis of sensory assessment and volatile analysis, high pressure treatment at 800 MPa does not seem to be suitable for preserving fresh tomato odour.     

超声波辅助提取水酶法豆渣中植酸的工艺优化

以水酶法提油后的副产物豆渣为原料,探索超声波辅助技术提取植酸的工艺条件,并与振荡浸提法对比。首先选取超声功率、超声温度、超声时间进行单因素实验,通过正交实验选出最佳的超声参数。然后在最优超声参数的基础上,以植酸得率为响应值,利用Box-Behnken中心组合设计原理和响应面分析法,确定提取植酸的最佳条件。结果表明,超声提取植酸的条件为:超声温度50℃,超声功率500 W,超声时间20 min;醋酸浓度4.1%、料液比1∶17 g/m L、提取温度64℃、提取时间33 min。在以上条件下,平均植酸得率为1.23%,与振荡提取法相比,提高41.3%。      

Effects of high-pressure processing on proteolytic enzymes and proteins in cold-smoked salmon during refrigerated storage

The present paper describes the effects of high-pressure processing on the activity of proteolytic enzymes in cold-smoked salmon and enzyme extracts for pressures up to 300 MPa. The activities of the three enzymes, cathepsin B-like, cathepsin B + L-like and calpains were reduced at all pressure levels of up to 300 MPa (at ca. 9 °C for 20 min) in crude enzyme extracts prepared from cold-smoked salmon. Calpain almost completely inactivated at 300 MPa. High-pressure did not influence general proteolytic activity but activated the enzymes in muscles at higher pressure levels studied until 18 days of storage. An increase in the activity of cathepsin B + L-like and calpain was seen after 12 days of refrigerated storage. Myosin heavy chain was less affected at higher pressure levels (300 MPa) only as shown by Sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) of proteins and further refrigerated storage had no obvious effects on proteins.     

Effects of processing conditions on the chemical distribution of mate tea leaves extracts obtained from CO2 extraction at high pressures

This work reports the effects of industrial manufacturing steps on the distribution of chemical components of the extracts obtained from supercritical carbon dioxide (SCCO₂) of processed mate tea leaves. For this purpose, samples of mate tea leaves were collected from the actual industrial processing after the fast pre-heating, drying and storage (5 and 21 days) steps. To provide a consistent basis for comparisons, extractions were also conducted for the unprocessed leaves fed in the industrial environment. In order to select the appropriate extraction parameters at high pressure, it was evaluated the effects of temperature from 15 to 55 °C and pressure from 10 to 20 MPa on the liquid yield of unprocessed mate tea leaves. The SCCO₂ extraction experiments regarding the effects of industrial processing conditions were then performed at 35 °C and 20 MPa and the extract chemical analyses were carried out in a GC/MSD. Results show that the extraction yield and chemical composition of the extracts are strongly affected by the industrial processing steps. Chromatographic analyses permitted the identification of caffeine, theobromine, hexadecanoic acid, phytol, squalene, octacosanol, 2-heptacosanone, steroids and triterpenes as the main constituents in the extracts.     

Effects of lipid,PET/PE and PA/PE with high-pressure processing

The mutual effects between food components and packaging materials under high-pressure processing was investigated. Pouches made of Polyethylene terephthalate/Polyethylene and Polyamide/Polyethylene packaging olive oil and glycerol trioleate were subjected to different pressures and holding times, and then stored at 23 ± 2^oC for 40 days. The results proved that there were significant effect between lipid and packaging under high-pressure processing treatment. High pressure would be beneficial to extend food shelf life and affect the enthalpy of fusion of packaging materials, especially when making contact with olive oil which probably acted as a plasticizer to change the polymer structure.     

大豆低聚糖在碱液中的浸出及在食品中的加工特性

研究发现在碱液中大豆低聚糖的浸出率明显提高。确定了合适的浸泡时间和碱液浓度，同时还对大豆低聚糖在食品中的加工特性进行了研究。     

Effect of pH,temperature and maturity on pectinmethylesterase inactivation of citrus juices treated by high-pressure homogenization

The effects of high-pressure homogenization (HPH) at 150 MPa combined with heating at 58, 63 and 68 °C on inactivation of pectinmethylesterase (PME) were studied in orange and Clementine juices. Juices covering a range of total soluble solids (°Bx) to acid ratios (10.2–15.0 in oranges and 9.2–19.4 in Clementines) were adjusted to pH 3.1, 3.5 and 3.9 before homogenization. Results indicated how the residual PME activity of homogenized samples was greatly attenuated by lowering the pH and in a lesser extent by increasing the homogenization temperature (finding orange enzymes more HPH sensitive than their Clementine counterparts). Generally, ripeness of fruits had little influence on PME inactivation (especially in Clementine juices). In any case, orange and Clementine samples with pH 3.1 and homogenized at 68 °C showed residual PME activities below 10% of the initial value from their respective fresh juices.